[Qemu-devel] [PATCH RFC 4/9] tcg/optimize: add optimizations for ext_i32_i64 and extu_i32_i64 ops

[Aurelien Jarno]

They behave the same as ext32s_i64 and ext32u_i64 from the constant
folding and zero propagation point of view, except that they can't
be replaced by a mov, so we don't compute the affected value.

Cc: Paolo Bonzini <address@hidden>
Cc: Richard Henderson <address@hidden>
Signed-off-by: Aurelien Jarno <address@hidden>
---
 tcg/optimize.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tcg/optimize.c b/tcg/optimize.c
index d66373d..18b7bc3 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -347,9 +347,11 @@ static TCGArg do_constant_folding_2(TCGOpcode op, TCGArg 
x, TCGArg y)
     CASE_OP_32_64(ext16u):
         return (uint16_t)x;
 
+    case INDEX_op_ext_i32_i64:
     case INDEX_op_ext32s_i64:
         return (int32_t)x;
 
+    case INDEX_op_extu_i32_i64:
     case INDEX_op_ext32u_i64:
         return (uint32_t)x;
 
@@ -839,6 +841,14 @@ void tcg_optimize(TCGContext *s)
             mask = temps[args[1]].mask & mask;
             break;
 
+        case INDEX_op_ext_i32_i64:
+            if ((temps[args[1]].mask & 0x80000000) != 0) {
+                break;
+            }
+        case INDEX_op_extu_i32_i64:
+            mask = (uint32_t)temps[args[1]].mask;
+            break;
+
         CASE_OP_32_64(andc):
             /* Known-zeros does not imply known-ones.  Therefore unless
                args[2] is constant, we can't infer anything from it.  */
-- 
2.1.4